Dual pumping arrangement for a hollow fiber filter

ABSTRACT

A fluid filtration assembly includes a filter housing having first and second ends and a connector for fluid communication with a fluid storage vessel. A filter element is disposable within the filter housing, and first and second pumps are coupled at the first and second ends of the filter housing. A controller may coordinate the operation of the first and second pumps to induce alternating tangential flow of fluid between the filter housing and the first and second pumps. At least one of the first and second pumps is a diaphragm pump or a plunger pump. The fluid storage vessel can be a bioreactor.

BACKGROUND OF THE DISCLOSURE Field of the Disclosure

Embodiments of the disclosure relate generally to filtration systems,and more particularly to an alternating tangential flow filtration unitthat includes a housing and first and second pumps for alternating flowthrough a filter element disposed in the housing.

Discussion of Related Art

Filtration is typically performed to separate, clarify, modify, and/orconcentrate a fluid solution, mixture, or suspension. In thebiotechnology, pharmaceutical, and medical industries, filtration isvital for the successful production, processing, and analysis of drugs,diagnostics, and chemicals as well as many other products. As examples,filtration may be used to sterilize fluids and to clarify a complexsuspension into a filtered “clear” fraction and an unfiltered fraction.Similarly, constituents in a suspension may be concentrated by removingor “filtering out” the suspending medium. Further, with appropriateselection of filter material, filter pore size and/or other filtervariables, many other specialized uses have been developed. These usesmay involve selective isolation of constituents from various sources,including cultures of microorganisms, blood, as well as other fluidsthat may be solutions, mixtures, or suspensions.

Biologics manufacturing processes have advanced through substantialprocess intensification. Both eukaryotic and microbial cell culture toproduce recombinant proteins, virus-like particles (VLP), gene therapyparticles, and vaccines now include cell growth techniques that canachieve 100e6 cells/ml or higher. This is achieved using cell retentiondevices that remove metabolic waste products and refresh the culturewith additional nutrients. One of the most common means of cellretention is to perfuse a bioreactor culture using hollow fiberfiltration using alternating tangential flow (ATF). Commercial anddevelopment scale processes use a device that controls a pump to performATF through a hollow fiber filter.

As shown in FIG. 1, a hollow fiber filter module 1 is verticallyoriented, with a diaphragm pump 2 conventionally located on the bottomend 4 of the hollow fiber filter module. An inlet and return 6 from andto a vessel, such as a bioreactor vessel (not shown), is positioned on aside of the filter module 1 opposite the pump 2. The hollow fiber filter8 is thus positioned between the vessel and the pump 2. As will beappreciated, the hollow fiber filter 8 represents a restriction in theflow of liquid between the pump 2 and the vessel, and as a result, thehollow fiber filter is not uniformly utilized along its entire length.

In addition, the use of a single diaphragm pump in such an arrangementhas inherent limitations because it uses a vacuum on the underside ofthe diaphragm during the “pull” cycle in order to draw liquid from theprocess vessel down through the filter. The maximum “vacuum” that can beapplied, however, is about −14.5 psi. This vacuum can be furtherimpacted by losses in the tubing/piping and components between thevacuum source and the diaphragm pump. In addition, if the viscosity ofthe fluid changes, there may be a requirement for more negative pressurebehind the diaphragm to obtain a full displacement of the pump. All ofthese factors can reduce the efficiency of conventional pumping systems.

It would be desirable, therefore, to provide an improved pumpingarrangement that increases the utilization of the entire filter lengthof a hollow fiber filter used in connection with a vessel such as abioreactor vessel. It would also be desirable to provide a pumpingarrangement that enhances the overall efficiency of the pumping system.

SUMMARY OF THE DISCLOSURE

A fluid filtration assembly is disclosed, including a filter housinghaving first and second ends, and a coupling for fluid connection with afluid storage vessel. A filter element may be disposable within thefilter housing. A first pump is coupled at the first end of the filterhousing and a second pump is coupled at the second end of the filterhousing. The first and second pumps can be configured to move fluid fromthe fluid storage vessel through the filter element.

In some embodiments, at least one of the first and second pumps is adiaphragm pump or a plunger pump. The filter element can be a hollowfiber filter. The first and second pumps can be controllable to generatealternating tangential flow of the fluid between the filter housing andthe first and second pumps. The first and second pumps can be separatelycontrollable. The first and second pumps can be controllable such that avacuum stroke of the first pump is synchronized with a pressure strokeof the second pump. The first and second pumps can be controllable sothat a diaphragm of the first pump applies a positive pressure to thefluid while a diaphragm of the second pump is under negative pressure.

A fluid filtration assembly is disclosed, including a process vessel, afilter housing having first and second ends, and a coupling for fluidcommunication with the process vessel. A filter element can be disposedwithin the filter housing. A first pump is coupled at the first end ofthe filter housing and a second pump is coupled at the second end of thefilter housing. The first and second pumps can be configured to movefluid from the fluid storage vessel through the filter element.

At least one of the first and second pumps can be a diaphragm pump or aplunger pump. The filter element can be a hollow fiber filter. The firstand second pumps can be controllable to generate alternating tangentialflow of the fluid between the filter housing and the first and secondpumps. The system can include a controller including a processorprogrammed to execute instructions to control the first and secondpumps. The processor may be programmed to execute instructions tocontrol the first and second pumps so that a vacuum stroke of the firstpump is synchronized with a pressure stroke of the second pump. Theprocessor may be programmed to execute instructions to control the firstand second pumps so that a diaphragm of the first pump applies apositive pressure to the fluid while a diaphragm of the second pump isunder negative pressure.

A fluid filtration assembly is disclosed, and includes a process vessel,a filter housing having first and second ends, and a coupling for fluidcommunication with the process vessel. A filter element is disposablewithin the filter housing. A first pump is coupled at the first end ofthe filter housing and a second pump coupled at the second end of thefilter housing. The first and second pumps can be configured to movefluid from the fluid storage vessel through the filter element. Acontroller can be in communication with the first and second pumps forsimultaneously actuating the first and second pumps to cycle fluidbetween the first and second pumps and the process vessel.

At least one of the first and second pumps is a diaphragm pump or aplunger pump. The controller comprises a processor programmed to executeinstructions to control operation of the first and second pumps. Theprocessor may be programmed to execute instructions to control the firstand second pumps to generate alternating tangential flow of the fluidbetween the filter housing and the first and second pumps. The processormay be programmed to execute instructions to control the first andsecond pumps so that a vacuum stroke of the first pump is synchronizedwith a pressure stroke of the second pump. The processor may beprogrammed to execute instructions to control the first and second pumpsso that a diaphragm of the first pump applies a positive pressure to thefluid while a diaphragm of the second pump is under negative pressure.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate preferred embodiments of thedisclosed method so far devised for the practical application of theprinciples thereof, and in which:

FIG. 1 is an isometric view of a conventional filter module anddiaphragm pump arrangement;

FIG. 2 is a side view of an example pump and filter assembly accordingto the present disclosure;

FIG. 3 is a cross-section view of the pump and filter assembly of FIG. 2taken along line 3-3 of FIG. 2;

FIGS. 4 and 5 are cross-section views of example diaphragm pumps for usewith the pump and filter assembly of FIG. 2;

FIG. 6 is a cross-section view of an example plunger pump for use withthe pump and filter assembly of FIG. 2; and

FIG. 7 is a schematic of an example control system for use with the pumpand filter assembly of FIG. 2.

DESCRIPTION OF EMBODIMENTS

A pump and filter assembly is disclosed, comprising a filter housingcontaining a filter, and first and second pumps which move fluid inalternating directions through the filter. In some embodiments, thefilter housing is connected to a vessel, such as a bioreactor vessel,for filtering the contents thereof. The assembly can be employed forconducting a rapid, low sheer, Alternating Tangential Flow (ATF) offluid through the filter, which in some embodiments is a hollow fiberfilter. Such a system has applications in perfusion of cultured animalcells as well as other varied filtration applications.

As will be discussed in greater detail later, the disclosed assembly canprovide a more uniform use of the filter as compared to current systems.By employing two pumps positioned at opposite ends of the filter, and bysynchronizing the action of both pumps, a more robust pumping action andmore uniform filter utilization can be achieved compared to currentsystems that use only a single pump. In some embodiments, the two pumpsare independently controlled, which can provide an additional degree offlow controllability. Further, operational control of the two pumps canbe based on an algorithm which can periodically apply an operationalsubroutine that facilitates a filter cleaning/backflush function. Theseand other advantage will be discussed below.

FIGS. 2 and 3 illustrate an example pump and filter assembly 10, whichcan include a filter housing 12 having first and second ends 14, 16. Thefilter housing 12 encloses a filter element 13, which in onenon-limiting exemplary embodiment, is a hollow fiber filter. A firstpump 18 is coupled to the first end 14 of the filter housing 12 and asecond pump 20 is coupled the second end 16 of the filter housing. Inthe illustrated embodiment the first and second pumps 18, 20 arediaphragm pumps, but it will be appreciated that the disclosure is notso limited, and thus the first and second pumps can be any appropriatepump type, including plunger pumps and the like. In addition, the firstand second pumps 18, 20 may be different pump types, and/or may be ofdifferent sizes, capacities, etc. In some embodiments, the pump andfilter assembly 10 is a single use integral assembly for filtering fluidstored in a process vessel (not shown).

The pump and filter assembly 10 can include a fluid connection port 22disposed in the filter housing 12 for coupling the pump and filterassembly to a process vessel to receive fluid from the vessel and toprovide filtered fluid back to the vessel. The pump and filter assembly10 can also include a plurality of ports, such as a fluid harvest port24 for removing filtered fluid from the filter housing, a fluidmonitoring port 26 for coupling a pressure valve or transducer, and afluid sample port 28 for coupling a sampler valve. As will beappreciated, a sampler valve may be used for sampling the quality of thefluid in the first pump 18, injecting or expelling liquid or gas intoand out of the pump, and injecting sterilizing steam into the systemand/or removing resulting steam condensate from the system.

Although not shown, the process vessel may be any suitable container forhousing a fluid to be filtered. For example, it may be a bioreactor, afermentor or any other vessel, nonexclusively including vats, barrels,tanks, bottles, flasks, containers, and the like which can containliquids. The process vessel may be composed of any suitable materialsuch as plastic, metal such as stainless steel, glass, or the like.Appropriate fluid connectors (piping, tubing, couplings, valves) can beused to fluidly couple the process vessel to the pump and filterassembly 10.

The filter housing 12 can be made from plastic, metal, such as stainlesssteel, glass, and the like. Suitable filter elements 13 include hollowfiber filters, screen filters, and the like. In one non-limiting exampleembodiment, the filter element 13 is a hollow fiber filter. According tothe disclosure, pump and filter assembly 10 can be configured for singleuse (i.e., disposable), with the filter housing 12, filter element 13and first and second pumps 18, 20 provided together as an integralassembly. Alternatively, in some embodiments only the filter housing 12and filter element 13 may be configured for single use, and may beremovably connectable to the first and second pumps 18, 20, one or bothof which may be reusable.

Various advantages exist in providing the pump and filter assembly 10 asa single-use (disposable) assembly. For example, the assembly can be setup with minimal handling and do not require cleaning or sterilization bythe user, since the components are supplied sterile and in a form readyto use with minimal preparation and assembly. This can result in costsavings due to reduced labor and handling by the user along withelimination of a long autoclave cycle. Furthermore, at the end of theiruse, the assembly can be readily discarded without cleaning. Adisposable assembly reduces risk of contamination and assembly byoperators, and do not require lengthy validation procedures foroperation/sterilization. The components of the assembly also can belighter and easier to transport, and are less expensive and take up lessstorage space compared to stainless steel or glass units.

FIG. 4 shows an exemplary diaphragm pump 30 for use as the first pump 18illustrated in FIGS. 2 and 3. In general, the diaphragm pump 30 includesa pump housing 32 separated into first and second interior chambers 34,36 by an internal flexible diaphragm 38. The pump 30 is actuated byfeeding compressed air into the first chamber 34 of the pump via a gasinlet 40, filling the first chamber with the gas, and forcing thediaphragm 38 to expand the first chamber and to move fluid in the secondchamber 36 so that it passes through the filter element 13 and into (viafluid connection port 22) an attached process vessel, such as abioreactor vessel. When the gas is drawn back through the gas inlet 40,such as by a vacuum source, the diaphragm 38 is drawn towards the gasinlet, which causes the first chamber 34 to decrease in volume, anddraws flow from the process vessel (via fluid connection port 22)through the filter element 13 and into the expanding second chamber 36.This action can be repeated, drawing fluid back and forth from theprocess vessel, through the filter element 13, and second chamber 36,thereby causing an alternating flow tangentially through the filter.

FIG. 5 shows an exemplary diaphragm pump 42 for use as the second pump20 illustrated in FIGS. 2 and 3. In general, the diaphragm pump 42 issimilar in form and function to the diaphragm pump 30 shown in FIG. 4.Thus, the diaphragm pump 42 includes a pump housing 44 separated intofirst and second interior chambers 46, 48 by an internal flexiblediaphragm 50. The pump 42 is actuated by feeding compressed air into thefirst chamber 46 of the pump via a gas inlet 52, filling the firstchamber with the gas, and forcing the diaphragm 50 to expand the firstchamber and to move fluid in the second chamber 36 so that it passesdownward through the filter element 13. When the gas is drawn backthrough the gas inlet 52, such as by a vacuum source, the diaphragm 50is drawn towards the gas inlet, which causes the first chamber 46 todecrease in volume, and draws upward through the filter element 13toward the expanding second chamber 48. This action can be repeated,drawing fluid back and forth from the process vessel, through the filterelement 13, and second chamber 48, thereby causing an alternating flowtangentially through the filter element.

With the disclosed arrangement, pumping can consist of two cycles, apressure cycle and a vacuum cycle. The vacuum cycle under the diaphragm38 (referred to as the air side) pulls liquid from the process vesselthrough the filter element 13, while the pressure cycle under thediaphragm 38 pushes the liquid through the filter into the processvessel. The liquid is filtered, and a portion is evacuated as a filtratefrom the fluid harvest port 24, while a portion of volume of liquid,during the pressure part of the cycle, is returned to the process vesselthrough fluid connection port 22. The volume difference between theliquid returned to the process vessel and the volume of filtratecollected via the fluid harvest port 24 is constant, and is dependent onthe size of the hollow fiber filter element 13, as well as processrequirements.

In some embodiments, the first and second pumps 18, 20 can beproportionally sized (e.g., the first pump would have a differentdisplacement volume than the second pump, or the first pump would have adifferent stroke than the second pump) to reflect a desired flowdistribution between the process vessel and filtrate collection. Forexample, the upper and lower pump volume difference can be used toprovide desired liquid exchanges between the process vessel and thefilter element 13, as well as desired filtrate collection volumes. Aswill be understood, to reduce the chance for cell damage residence timeof a cell culture outside of the process vessel (i.e., in the region ofthe filter element 13 and first and second pumps 18, 20) should beminimized. By implementing a volume difference between the first andsecond pumps 18, 20, the liquid exchanges temporarily contained in thefilter and pump can be controlled and enhanced.

As previously noted, the disclosed arrangement provides increasedrobustness in pumping when operation of the first and second pumps 18,20 are synchronized. For example, it will be appreciated that in someembodiments the vacuum stroke of the first pump 18 can be synchronizedwith the positive pressure stroke of the second pump 20, and vice versa.That is, as the diaphragm of one pump applies positive pressure to thefluid, the diaphragm of the other pump is under negative (i.e., vacuum)pressure. Such complimentary operation of the first and second pumps 18,20 can enhance overall effectiveness of pumping of the process liquidthrough the filter element 13, since the vacuum stroke of each pump willbe enhanced by the positive pressure stroke of the opposite pump.

The benefit of such an arrangement is that positive pressure is limitedonly by the characteristics of the pump, and thus the positive pressurestroke of the pumps 18, 20 provides the more robust portion of thecycle. Negative pressure availability is naturally limited, and thus thenegative pressure stroke of the pumps 18, 20 is the weaker part of thecycle. By providing liquid movement assist via one pump in the positivepressure mode, while the other pump is in the negative pressure mode,makes the overall pumping action stable and uniform.

In some embodiments, the negative pressure stroke(s) may be eliminatedentirely from the overall pumping cycle. In such arrangements,alternating positive pressure strokes between the first and second pumps18, 20 may be used to move fluid back and forth with respect to thefilter element 13. For example, when positive pressure is applied to oneof the pumps 18, 20, the opposite pump 20, 18 may be allowed to movefreely (i.e., the associated diaphragm 38, 50 is simply allowed to bemoved by the motion of the fluid). On the end of each positive pressurestroke, the “free” moved pump takes over, and under positive pressuremoves the liquid while the opposite pump is allowed to move freely. Suchan arrangement would eliminate the need for a vacuum source to beapplied to the first and second pumps 18, 20, thus simplifying theoverall system.

In some embodiments, the first and second pumps 18, 20 are controlledindependently, providing additional variability in the control of fluidthrough the filter element 13. This control can be either manual orautomated. Thus, operation of the first and second pumps 18, 20 can becontrolled by an algorithm, which can be selectable by a user, or may insome cases be automatically selected based on the type and size offilter element 13, the type of fluid being filtered, and the like.

As will be described in greater detail later, in some embodiments,actuation of the first and second pumps 18, 20 will be controlled bycontroller 76 including a microprocessor or programmable logic circuit(PLC) which allows the system to operate the pumps in a variety ofsequences and manners. For example, the processor of the controller 76could execute instructions (e.g., a subroutine) to apply a temporarydifference in stroke sequence between the first and second pumps 18, 20.Such operation may offer beneficial benefits to the process or longevityof the filter. As will be appreciated, the controller 76 may apply anyof a variety of adjustments to pump operation, which can be stored incontroller memory and executed by the controller processor upon usercommand or automatically.

As previously noted, one or both of the first and second pumps 18, 20may be of a type other than a diaphragm pump. FIG. 6 shows an exemplaryplunger pump 54 for use as the first and/or second pump 18, 20illustrated in FIGS. 2 and 3. The plunger pump 54 can include a housingportion 56 and an actuator portion 58. The housing portion 56 mayinclude a rigid portion 60 and a flexible portion 62 coupled together.The flexible portion 62 may also be coupled to the actuator portion 58so that the flexible portion 62 is movable with respect to the rigidportion 60 in response to activation of the actuator portion. Theactuator portion 58 may include a cylinder housing 64, and a driven rodportion 66 that is selectively movable within the cylinder housing. Aservo motor, cam, pneumatic or electrical actuator can be used toselectively move the rod portion 66 in the directions of arrows “A” and“B” to cause the plunger pump 54 to move fluid through the filterelement 13 in manner similar to that described in relation to thediaphragm pump 30 illustrated in FIG. 4.

As best seen, the rigid portion 60 and flexible portion 62 of thehousing 56 can each be bell-shaped members that can be coupled togetherto provide the housing portion with a globe shape having an interiorvolume 68 defined by respective inner surfaces of the rigid and flexibleportions. The rigid portion 60 and flexible portion 62 have respectiveradially extending flanges 70, 72 that can contact each other and can beclamped together via clamp or nut 74. Alternatively, the flexibleportion 62 can be formed from an elastomer that is overmolded on therigid portion 60, thus eliminating the need for a clamp 74.

As will be appreciated, expansion or contraction of the flexible portion62 can generate vacuum and pressure required to initiate movement offluid between the first pump 18 and the process vessel. Where the secondpump 20 is a plunger pump similar to that described in relation to FIG.6, operation of the first and second pumps 18, 20 can be synchronized ina similar fashion to that previously described, such that the first andsecond pumps complement each other. For example, the “vacuum” stroke ofeach pump will be enhanced by the “pressure” stroke of the opposite pumpwhen the pumps 18, 20 are synchronized (i.e., one flexible portion 62applies pressure when the other pump is at vacuum.)

In some embodiments, operation of the first and second pumps 18, 20 canbe automated via a controller. FIG. 7 shows a controller 76 coupled tothe first and second pumps 18, 20 via first and second gas inlet/exhaustlines 78, 80, for controlling the movement of the diaphragms 38, 50within the first and second pumps. The controller 76 may include gassupply and exhaust lines 82, 84 connected to gas service infrastructureof a building or the like. By controlling the pressure applied behindthe diaphragms 38, 50, the controller 76 can control the flow of fluidflow back and forth through the filter element 13 according to a desiredset of cycle parameters.

As previously mentioned, the controller 76 can include a processor andassociated memory for storing information regarding the first and secondpumps 18, 20, the filter element 13 and/or other aspects of the system.The memory can include instructions executable by the processor forcontrolling operation of the first and second pumps 18, 20 to therebycontrol flow of fluid back and forth through the filter element 13 inany of a variety of desired manners. The controller 76 can also includea user interface for allowing a user to input information into thecontroller and/or operate the controller and the associated first andsecond pumps 18, 20 in a desired manner.

Although in the illustrated embodiment the controller 76 is shown asbeing coupled to the first and second pumps 18, 20 via first and secondgas inlet/exhaust lines 78, 80, it will be appreciated that when thefirst and second pumps are not diaphragm pumps, other connection typescan be used. For example, where one or both of the first and secondpumps 18, 20 is a plunger pump (FIG. 6), the controller 76 may becoupled to the actuator portion(s) 58 via a hard-wired or wirelessconnection to control the pump(s) in a desired manner to control flow offluid back and forth through the filter element 13.

In use, the first and second pumps 18, 20 can generate an alternatingtangential flow through the filter element 13. The first and secondpumps 18, 20 can generate a reversible flow of liquid such as a culturesuspension, back and forth, between the process vessel and the firstpump 18. For example, flow from the housing 12 through the filterelement 13 to the process vessel is generated by applying positivepressure beneath the diaphragm 38 of the first pump 18, and by applyingvacuum pressure above the diaphragm 50 of the second pump 20. Movementof diaphragm 38 of the first pump 18 expels liquid from the housing 32of the first pump, moving the liquid towards the process vessel, andgenerating a tangential flow in one direction. Final, filtered productis removed through harvest port 24 by, for example, a peristaltic pump.In the reverse, flow from the process vessel through the filter element13 and housing 12 is generated by applying positive pressure above thediaphragm 50 of the second pump 20, and by applying negative pressurebeneath the diaphragm 38 of the first pump 18. Final, filtered productis removed through harvest port 24 by, for example, a peristaltic pump.Flow from pump 24 to the process vessel and return from the processvessel to the pump 24 completes one cycle.

While the present invention has been disclosed with reference to certainembodiments, numerous modifications, alterations and changes to thedescribed embodiments are possible without departing from the spirit andscope of the invention, as defined in the appended claims. Accordingly,it is intended that the present invention not be limited to thedescribed embodiments, but that it has the full scope defined by thelanguage of the following claims, and equivalents thereof.

What is claimed is:
 1. A fluid filtration assembly, comprising: a filterhousing having first and second ends, and fluidly communicating with afluid storage vessel; a filter element disposable within the filterhousing; and a first pump coupled to the first end of the filter housingand a second pump coupled to the second end of the filter housing, thefirst and second pumps operable for pumping fluid from the fluid storagevessel through the filter element.
 2. The fluid filtration assembly ofclaim 1, wherein at least one of the first and second pumps is adiaphragm pump.
 3. The fluid filtration assembly of claim 1, wherein atleast one of the first and second pumps is a plunger pump.
 4. The fluidfiltration assembly of claim 1, wherein the filter element is a hollowfiber filter.
 5. The fluid filtration assembly of claim 4, wherein thefirst and second pumps are controllable to generate alternatingtangential flow of the fluid between the filter housing and the firstand second pumps.
 6. The fluid filtration assembly of claim 1, whereinthe first and second pumps are separately controllable.
 7. The fluidfiltration assembly of claim 1, wherein the first and second pumps arecontrollable such that a vacuum stroke of the first pump is synchronizedwith a pressure stroke of the second pump.
 8. The fluid filtrationassembly of claim 1, wherein the first and second pumps are controllableso that a diaphragm of the first pump applies a positive pressure to thefluid while a diaphragm of the second pump is under negative pressure.9. A fluid filtration assembly, comprising: a process vessel; a filterhousing having first and second ends, and fluidly communicating with theprocess vessel; a filter element disposable within the filter housing;and a first pump coupled to the first end of the filter housing and asecond pump coupled to the second end of the filter housing, the firstand second pumps operable for pumping fluid from the process vesselthrough the filter element.
 10. The fluid filtration assembly of claim9, wherein at least one of the first and second pumps is a diaphragmpump.
 11. The fluid filtration assembly of claim 9, wherein at least oneof the first and second pumps is a plunger pump.
 12. The fluidfiltration assembly of claim 9, wherein the filter element is a hollowfiber filter.
 13. The fluid filtration assembly of claim 12, wherein thefirst and second pumps are controllable to generate alternatingtangential flow of the fluid between the filter housing and the firstand second pumps.
 14. The fluid filtration assembly of claim 12, furthercomprising a controller including a processor programmed to executeinstructions to control the first and second pumps.
 15. The fluidfiltration assembly of claim 14, wherein the processor is programmed toexecute instructions to control the first and second pumps so that avacuum stroke of the first pump is synchronized with a pressure strokeof the second pump.
 16. The fluid filtration assembly of claim 14,wherein the processor is programmed to execute instructions to controlthe first and second pumps so that a diaphragm of the first pump appliesa positive pressure to the fluid while a diaphragm of the second pump isunder negative pressure.
 17. A fluid filtration assembly, comprising: aprocess vessel; a filter housing having first and second ends, andfluidly communicating with the process vessel; a filter elementdisposable within the filter housing; a first pump coupled to the firstend of the filter housing and a second pump coupled to the second end ofthe filter housing, the first and second pumps operable for pumpingfluid from the process vessel through the filter element; and acontroller in communication with the first and second pumps configuredto actuate the first and second pumps to cycle fluid between the firstand second pumps and the process vessel.
 18. The fluid filtrationassembly of claim 17, wherein at least one of the first and second pumpsis a diaphragm pump or a plunger pump.
 19. The fluid filtration assemblyof claim 17, wherein the controller comprises a processor programmed toexecute instructions to control operation of the first and second pumps.20. The fluid filtration assembly of claim 19, wherein the processor isprogrammed to execute instructions to control the first and second pumpsto generate alternating tangential flow of the fluid between the filterhousing and the first and second pumps.
 21. The fluid filtrationassembly of claim 19, wherein the processor is programmed to executeinstructions to control the first and second pumps so that a vacuumstroke of the first pump is synchronized with a pressure stroke of thesecond pump.
 22. The fluid filtration assembly of claim 19, wherein theprocessor is programmed to execute instructions to control the first andsecond pumps so that a diaphragm of the first pump applies a positivepressure to the fluid while a diaphragm of the second pump is undernegative pressure.